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Ohm's Law Calculator — Solve V, I or R From the Other Two
Enter any two of voltage, current and resistance to solve for the third using Ohm's Law (V = I × R), with power (P = V × I) calculated alongside — the single most-used formula in basic circuit analysis, solved instantly instead of rearranging it by hand.
How to use Ohm's Law
- Enter any two of voltage, current or resistance.
- Read the calculated third value.
- Check the calculated power alongside it.
Frequently asked questions
- What is the actual Ohm's Law formula?
- V = I × R, where V is voltage in volts, I is current in amps, and R is resistance in ohms — rearranged as I = V/R or R = V/I depending on which value you are solving for.
- How is power calculated from these values?
- P = V × I (watts = volts × amps) — once you know voltage and current, power follows directly, which is why it is shown alongside the Ohm's Law result.
- Does this work for AC circuits with reactance?
- This is the basic DC/resistive form; AC circuits with reactive components need impedance-based calculations (see AC Impedance) rather than simple resistance.
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